Ion traps are used in numerous applications in molecular physics, and in particular in the ion cyclotron resonance phenomena implemented, for example, in Fourier transform mass spectrometers or FTICRs.
Such magnetic traps for ions enable the ions to be held captive in a defined volume in order to perform various measurements such as detecting cyclotron movements.
Conventionally, magnetic traps for ions implement means for generating a uniform magnetic field of high intensity, said means comprising solenoids that are resistive or superconductive.
Such generator means enable magnetic fields to be obtained of high intensity that can be as great as 9.4 teslas (T) and they present great stability over time.
Nevertheless, such components are very bulky and can weigh several tons. In addition, they require complex power supply and cooling installations and they are therefore suitable for use only in fixed installations.
In order to enable mobile devices to be developed, certain magnetic traps for ions make use of permanent magnets (L. C. Zeller, J. M. Kennady, J. E. Campana, H. I. Kentamaa, Anal. Chem. 1993, 65, 2116–2118, U.S. Pat. No. 5,451,781 in the name of Dietrich).
However, such permanent magnets generate fields that are generally limited to about 0.4 T and/or that are of volumes that are too small.
The qualities of an ion trap are associated with the uniformity and the intensity of the magnetic field to which it is subjected. Certain performance features of a trap vary as a function of the square of the intensity of the magnetic field and a minimum value of about 1 T is recommended for a high performance application to mass spectrometry of the FTICR type.
Siemens' “Advance quantra” mass spectrometer uses a permanent magnet generating a magnetic field of tesla order, but in order to do that, it requires a closed geometrical shape that is highly constraining.